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Other tools:

MX toolbox at https://mxtoolbox.com/
DNS Viz at https://dnsviz.net/
SSL Labs at https://www.ssllabs.com/ssltest/
Dns Dumpster at https://dnsdumpster.com
Free dyndns at https://freemyip.com
Shodan at https://shodan.io
Securitytrails at https://securitytrails.com/